diff --git a/ports/bsd/bip6.c b/ports/bsd/bip6.c
index 6babb427..bfc19c03 100644
--- a/ports/bsd/bip6.c
+++ b/ports/bsd/bip6.c
@@ -100,6 +100,7 @@ void bip6_debug_enable(void)
 
 /* unix socket */
 static int BIP6_Socket = -1;
+static int BIP6_Socket_Scope_Id = 0;
 /* local address - filled by init functions */
 static BACNET_IP6_ADDRESS BIP6_Addr;
 static BACNET_IP6_ADDRESS BIP6_Broadcast_Addr;
@@ -140,6 +141,7 @@ void bip6_set_interface(char *ifname)
                 ntohs(sin->sin6_addr.s6_addr16[7]));
             debug_print_ipv6(ifname, (&sin->sin6_addr));
             found = true;
+            BIP6_Socket_Scope_Id = if_nametoindex(ifname);
             break;
         }
         ifa_tmp = ifa_tmp->ifa_next;
@@ -274,6 +276,7 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     bvlc_dest.sin6_addr.s6_addr16[6] = htons(addr16[6]);
     bvlc_dest.sin6_addr.s6_addr16[7] = htons(addr16[7]);
     bvlc_dest.sin6_port = htons(dest->port);
+    bvlc_dest.sin6_scope_id = BIP6_Socket_Scope_Id;
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
     return sendto(BIP6_Socket, (char *)mtu, mtu_len, 0,
@@ -464,8 +467,8 @@ bool bip6_init(char *ifname)
         IP6_ADDRESS_MAX);
     memcpy(&join_request.ipv6mr_multiaddr, &broadcast_address,
         sizeof(struct in6_addr));
-    /* Let system choose the interface */
-    join_request.ipv6mr_interface = 0;
+    /* Let system not choose the interface */
+    join_request.ipv6mr_interface = BIP6_Socket_Scope_Id;
     status = setsockopt(BIP6_Socket, IPPROTO_IPV6, IPV6_JOIN_GROUP,
         &join_request, sizeof(join_request));
     if (status < 0) {
diff --git a/ports/linux/bip6.c b/ports/linux/bip6.c
index e457ec39..876cbccf 100644
--- a/ports/linux/bip6.c
+++ b/ports/linux/bip6.c
@@ -90,6 +90,7 @@ void bip6_debug_enable(void)
 
 /* unix socket */
 static int BIP6_Socket = -1;
+static int BIP6_Socket_Scope_Id = 0;
 /* local address - filled by init functions */
 static BACNET_IP6_ADDRESS BIP6_Addr;
 static BACNET_IP6_ADDRESS BIP6_Broadcast_Addr;
@@ -130,6 +131,7 @@ void bip6_set_interface(char *ifname)
                 ntohs(sin->sin6_addr.s6_addr16[7]));
             debug_print_ipv6(ifname, (&sin->sin6_addr));
             found = true;
+            BIP6_Socket_Scope_Id = if_nametoindex(ifname);
             break;
         }
         ifa_tmp = ifa_tmp->ifa_next;
@@ -264,6 +266,7 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     bvlc_dest.sin6_addr.s6_addr16[6] = htons(addr16[6]);
     bvlc_dest.sin6_addr.s6_addr16[7] = htons(addr16[7]);
     bvlc_dest.sin6_port = htons(dest->port);
+    bvlc_dest.sin6_scope_id = BIP6_Socket_Scope_Id;
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
     return sendto(BIP6_Socket, (char *)mtu, mtu_len, 0,
@@ -454,8 +457,8 @@ bool bip6_init(char *ifname)
         IP6_ADDRESS_MAX);
     memcpy(&join_request.ipv6mr_multiaddr, &broadcast_address,
         sizeof(struct in6_addr));
-    /* Let system choose the interface */
-    join_request.ipv6mr_interface = 0;
+    /* Let system not choose the interface */
+    join_request.ipv6mr_interface = BIP6_Socket_Scope_Id;
     status = setsockopt(BIP6_Socket, IPPROTO_IPV6, IPV6_JOIN_GROUP,
         &join_request, sizeof(join_request));
     if (status < 0) {
diff --git a/ports/win32/bip6.c b/ports/win32/bip6.c
index c3a297b5..fcd9ce3d 100644
--- a/ports/win32/bip6.c
+++ b/ports/win32/bip6.c
@@ -46,6 +46,7 @@
 
 /* Win32 Socket */
 static SOCKET BIP6_Socket = INVALID_SOCKET;
+static int BIP6_Socket_Scope_Id = 0;
 /* local address - filled by init functions */
 static BACNET_IP6_ADDRESS BIP6_Addr;
 static BACNET_IP6_ADDRESS BIP6_Broadcast_Addr;
@@ -207,8 +208,9 @@ void bip6_set_interface(char *ifname)
             IP6_ADDRESS_MAX);
         memcpy(&join_request.ipv6mr_multiaddr, &broadcast_address,
             sizeof(struct in6_addr));
-        /* Let system choose the interface */
-        join_request.ipv6mr_interface = 0;
+        /* Let system not choose the interface */
+        BIP6_Socket_Scope_Id = if_nametoindex(ifname);
+        join_request.ipv6mr_interface = BIP6_Socket_Scope_Id;
         RetVal = setsockopt(BIP6_Socket, IPPROTO_IPV6, IPV6_JOIN_GROUP,
             (char *)&join_request, sizeof(join_request));
         if (RetVal < 0) {
@@ -389,6 +391,7 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     bvlc_dest.sin6_addr.s6_addr16[6] = htons(addr16[6]);
     bvlc_dest.sin6_addr.s6_addr16[7] = htons(addr16[7]);
     bvlc_dest.sin6_port = htons(dest->port);
+    bvlc_dest.sin6_scope_id = BIP6_Socket_Scope_Id;
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
     return sendto(BIP6_Socket, (char *)mtu, mtu_len, 0,